the popup to insert a link fails on IE11.

test:

• mark any text, click on the link button
• using "other" in dropbox, insert any valid http://anything.here
• click ok

(note: result is exactly the same using any of the link types from the dropbox)

the resulting behaviour is different in 4.x and 5x.

• on 4.x
  a javascript error shows in the IE devtools console:
  "SCRIPT5007: Unable to get property 'nodeName' of undefined or null reference"

-on 5.x
popup closes, no error shows, but no link is created.